PARIS, France (CNN) -- A 24-hour walkout by French civil servants has coincided with the seventh straight day of crippling strikes by transit workers, putting further pressure on the French government to negotiate an end to the weeklong walkout.

The striking civil servants -- who include teachers, hospital workers, tax collectors, customs officials and post office staff -- planned a march Tuesday afternoon in Paris and other parts of the country.

The one-day civil servants strike was not expected to cripple those services, however. The teachers union said about half its members would still be in the classrooms, so classes would be combined to make up for the teacher absences.

The streets of Paris were already filled with traffic and pedestrians as commuters, unable to take the trains, resorted to other means to get to work. Cars competed for space with people on foot, bikes, scooters, and rollerblades.

A dwindling number of transport workers were supporting the open-ended walkout. The French railroad authority said just 25 percent of its workers were absent Tuesday and the rest were working, and the Paris subway authority said 19 percent of its staff were on strike.

Still, the small number of striking workers was able to disrupt services because it represented train drivers, conductors, and others crucial to the operation of the lines.

The French finance minister said Monday the strikes were costing the economy an estimated €350 million ($517 million) a day. "It's a real worry for the French economy," Christine Lagarde said.

Transport unions are striking over plans by French President Nicolas Sarkozy to reform a special category of pensions. The government is focusing on pension plans which allow some workers -- mostly train drivers -- to retire as early as 50.

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The French government continued to enjoy public support for its planned reforms, but the strikes were widely seen as a test of Sarkozy's political will. The government has so far stood firm in the face of the striking unions, refusing to negotiate on the central issue of retirement age.

But last week, the government offered to discuss all other outstanding issues and six of the striking unions agreed to discuss the proposals in a meeting scheduled for Wednesday, according to a spokesman for SNCF, the national rail authority.

Among the government's possible proposals is reforming the way pensions are calculated to give workers more pension money upon retirement.

About a half million out of 27 million French workers are eligible for the special retirement plan, which began during the era of steam trains.

The demands of the striking civil servants were less clear. They were demanding an increase in their buying power and protesting the elimination of about 22,000 civil sector jobs which the government has cut to save money.E-mail to a friend